The disclosure relates to coupling electronic devices with circuit boards, and more particularly to an adapter for electrically connecting a laser diode to a circuit board.
In optical communications, a laser diode transmits optical signals through an optical medium, such as an optical fiber cable. The optical signals are transmitted in response to electrical signals received through conductive electrodes of the laser diode, typically referred to as legs (e.g., two or more of which can protrude from the laser diode in parallel). Under a traditional approach, the legs of the laser diode are connected to conductors of a printed circuit board (PCB) by bending the legs and soldering each leg to the respective conductor. However, bending the legs may cause stress in an enclosure of the laser diode (e.g., by causing cracking in a glass feed-through of the laser diode and/or otherwise reducing mean time between failures), require complex labor which may not be able to be automated, and may require the legs to be relatively long so that they can be soldered in the same plane, which may negatively impact radio frequency performance, such as bandwidth.
One proposed solution to avoid bending the legs of the laser diode is presented in FIGS. 1-2B. FIG. 1 is a schematic diagram of a multilayer PCB 100 having a protruding portion 102 of some layers for coupling to a laser diode 104. FIG. 2A is a schematic cross-sectional view of the multilayer PCB 100 of FIG. 1 taken at line A-A, illustrating layers 200 of the multilayer PCB 100. Referring to FIGS. 1 and 2A, the laser diode 104 includes a base 106 through which elongate conductive contacts, leads or legs 108 extend. A through-hole 110 is formed in the multilayer PCB 100 in which the protruding portion 102 is disposed, and the laser diode 104 is positioned in the through-hole 110 and coupled to the protruding portion 102. The laser diode 104 is mounted to the multilayer PCB 100 by soldering the legs 108 to corresponding conductors 112 on the protruding portion 102.
In order to form the protruding portion 102, the multilayer PCB 100 includes the compound through-hole 110 and cavity 114 (e.g., cut-out). As illustrated in FIG. 2A, the through-hole 110 is defined by both upper and lower portions 202, 204 of the layers 200 of the multilayer PCB 100, and the cavity 114 is generally defined by the upper portion 202, wherein the cavity 114 is laterally open to the through-hole 110. This may be accomplished through techniques such as providing the upper portion 202 having the cavity 114 defined therein, providing the lower portion 204 having the through-hole 110 defined therein, and securing the upper portion 202 to the lower portion 204 in the stacked arrangement by laminating or other fastening techniques. The lower portion 204 also includes the conductors 112 which are electrically connected to the legs 108 of the laser diode 104. Electrical connections are also made between the upper portion 202 and the lower portion 204 of the multilayer PCB 100 to connect the conductors 112 to other components mounted on the multilayer PCB 100.
This technique of mounting the laser diode 104 to the multilayer PCB 100 at the protruding portion 102 seeks to overcome the problems described above from bending or otherwise deforming the legs 108 by providing the protruding portion 102 as a mounting point which avoids the need to deform the legs 108 of the laser diode 104. However, this technique requires complex manufacturing of the multilayer PCB 100, including forming separate upper and lower portions 202, 204 which are interconnected and laminated together. In addition, as depicted in FIG. 2B, mounting the laser diode 104 to the protruding portion 102 can place the laser diode 104 in an undesirable position for coupling to an optical fiber cable 206.
FIG. 2B is another schematic cross-sectional view of the multilayer PCB 100 of FIG. 1 taken at line A-A. As shown in FIG. 2B, an end of the laser diode 104 may be coupled to an end of an optical fiber cable 206 for transmitting optical signals through the optical fiber cable 206 in response to electrical signals being supplied to the laser diode 104 from the multilayer PCB 100 by way of the legs 108. By mounting the laser diode 104 to the protruding portion 102 of the multilayer PCB 100, the laser diode 104 is recessed into the through-hole 110 such that the optical fiber cable 206 must exit the through-hole 110, which requires forming a sharp bend 208 in the optical fiber cable 206. Such a sharp bend 208 in the optical fiber cable 206 can reduce performance and/or require a more costly transition interconnection between the laser diode 104 and the optical fiber cable 206.